A simmering row over German works of art looted by the Soviet Union at the end of Second World War bubbled over after Chancellor Angela Merkel and President Vladimir Putin abruptly cancelled the joint opening of a major Russian exhibition.

The German and Russian leaders had planned to hold speeches at St Petersburg’s Hermitage this evening to inaugurate the exhibition containing 600 pieces of looted German Bronze Age art. That plan was scrapped this morning because of Kremlin concerns that Ms Merkel would allude to Germany’s longstanding contention that Russia holds the artworks illegally and is morally obliged to return them. Hours later, the speech was reinstated, after the two sides agreed they would both make comments about the art.

“It is an important exhibition and we will both say something about it... This solves the problem,” Ms Merkel told Speigel.